It is known that certain natural antioxidants, such as plant flavonoids, inhibit both acute and chronic phases of free-radical induced diseases. Further, some natural antioxidants exhibit synergy in their reactions with biologically relevant oxygen species, e.g., hydroxyl radicals, superoxides, oxysulfurs, sulfur dioxide, and nitrogen dioxide. For example, studies have shown synergistic antioxidative activities of vitamin C and phenolic antioxidants.